Ion Gradients Drive Flooding in Membrane-Electrode Assembly CO2 Electrolyzers
Abstract
Low-temperature carbon dioxide electrolysis (CO 2 E) provides a low-carbon-emission pathway to basic chemical products. While anion exchange membrane (AEM)-based CO 2 E can provide high selectivity towards carbon products, runtimes are far below industry requirements. Flooding is a major obstacle to long-term stability as it limits CO 2 access to the catalyst layer, but the reasons for continuous water fluxes to the cathode are poorly understood. Here we present a model-aided experimental analysis of the driving forces for flooding. By tracking high-frequency resistance, anolyte conductivity, and cathode water accumulation over 24-hour runtimes across a range of current densities, temperatures and anolyte concentrations, we reveal AEM ion gradients as the main driving force for both flooding and cation-crowding at the cathode catalyst. We then show how ion gradient management can maintain steady CO selectivity and increase maximum CO 2 E partial current densities, with temperatures acting as a primary factor in reducing ion gradients. Using these insights, we demonstrate stable CO production at 500 mA cm -2 on an ionomer-free Ag catalyst.
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BibTeX
@misc{pelzer2026gradients,
title = {{Ion Gradients Drive Flooding in Membrane-Electrode Assembly CO2 Electrolyzers}},
author = {Henri M. Pelzer and Boris D. Wortmann and Samarinda M. de Heer and Eva Looijestein and David A. Vermaas and Thomas Burdyny},
howpublished = {ChemRxiv},
year = {2026},
month = oct,
doi = {10.26434/chemrxiv.15010385/v1},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15010385/v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - Ion Gradients Drive Flooding in Membrane-Electrode Assembly CO2 Electrolyzers
AU - Henri M. Pelzer
AU - Boris D. Wortmann
AU - Samarinda M. de Heer
AU - Eva Looijestein
AU - David A. Vermaas
AU - Thomas Burdyny
PY - 2026
DA - 2026/10/13
PB - ChemRxiv
DO - 10.26434/chemrxiv.15010385/v1
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15010385/v1
AB - Low-temperature carbon dioxide electrolysis (CO 2 E) provides a low-carbon-emission pathway to basic chemical products. While anion exchange membrane (AEM)-based CO 2 E can provide high selectivity towards carbon products, runtimes are far below industry requirements. Flooding is a major obstacle to long-term stability as it limits CO 2 access to the catalyst layer, but the reasons for continuous water fluxes to the cathode are poorly understood. Here we present a model-aided experimental analysis of the driving forces for flooding. By tracking high-frequency resistance, anolyte conductivity, and cathode water accumulation over 24-hour runtimes across a range of current densities, temperatures and anolyte concentrations, we reveal AEM ion gradients as the main driving force for both flooding and cation-crowding at the cathode catalyst. We then show how ion gradient management can maintain steady CO selectivity and increase maximum CO 2 E partial current densities, with temperatures acting as a primary factor in reducing ion gradients. Using these insights, we demonstrate stable CO production at 500 mA cm -2 on an ionomer-free Ag catalyst.
ER -